i just had my '01 xterra in the shop for the 3rd time for gas mileage - i went from getting 18mpg to 11mpg in 400 miles - they told me the only thing it was is the new tires (they are bigger)- when i told them i had the stock tires on they started back tracking and saying they couldnt find anything wrong - i am assuming they didnt look - i found the oil cap loose and thinking that might had something to do with it. maybe not but since it has been tightened up it i am getting a little better - ok i just looked this should be in the forum below - sorry